1. Field of the Invention
This invention relates to a retractor for use in laparoscopic surgery. In particular, the invention relates to a retractor that can be easily moved from a locked, straight position for insertion through a cannula, to an unlocked, self-forming curved or rounded position after the retractor is within the body.
2. The Prior Art
In laparoscopic surgery, the surgery is performed by making a small incision in the body and placing a cannula through the incision to the area to be operated on. The surgical instruments are then inserted through the cannula an manipulated from outside the body. Consequently, all of the instruments used in laparoscopic surgery must be small enough to fit through the cannula. It is often necessary during the surgery to move tissues or organs out of the way with a retractor. With large organs such as the liver, a retractor with a large surface area is needed. However, given the small diameter of the cannula, it is difficult to insert a suitable retractor into the surgical site.
There have been many attempts to devise a retractor that is suitable for laparoscopic or arthroscopic use. For example, U.S. Pat. No. 5,685,826 to Bonutti discloses a retractor having a mechanically expandible end portion. After the retractor is inserted into the surgical area, the tip of the retractor is pulled back, causing the side walls to fold outward, forming a plurality of radial arms.
Another retractor is produced by Genzyme Surgical Products. This retractor comprises a series of links held together by multiple cables. When the cables are tightened, the links form a predetermined shape. When the cables are loose, the links lie straight and can be fed through a cannula. The links are tightened by turning a screw until the desired shape is achieved.
While this device is an improvement over previous retractors, it is difficult to turn the screw and adjust the retractor during surgery.